Disc drives are used to store digitally encoded information on discs. Transducer elements read data from and write data to disc supported for rotation by a spindle motor. Transducer elements are supported above the disc surface by a head suspension assembly. Heads are positioned relative to data tracks via a voice coil motor. Disc drive density is increasing necessitating increased head positioning accuracy. Microactuators are used with a voice coil motor for adjusting head position for track placement. Microactuators include piezoelectric transducers on a head suspension assembly which receive a signal command from a controller to actuate the head.
Surfaces of the discs include asperities and other defects due to variations in the manufacturing process or created during shipping and handling or operation and use of the disc drive. During read write operations a head may contact asperities on the disc surface interfering with read/write operations. Contact between the head and disc surface can damage the disc surface and result in permanent data loss for a write command. Prior disc drives incorporate acoustic emission sensors attached to an E-block arm to determine head-disc contact. A sensor attached to an E-block arm sense head disc contact for some head on the E-block however its difficult to distinguish which head-disc interface is contacting. The present invention addresses these and other problems, and offers other advantages over prior art.